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Review
. 2023 Jan 26;205(1):e0033722.
doi: 10.1128/jb.00337-22. Epub 2023 Jan 4.

Mycobacterium smegmatis: The Vanguard of Mycobacterial Research

Ian L Sparks  1 , Keith M Derbyshire  2   3 , William R Jacobs Jr  4 , Yasu S Morita  1   5
Affiliations
Review

Mycobacterium smegmatis: The Vanguard of Mycobacterial Research

Ian L Sparks et al. J Bacteriol. .

Abstract

The genus Mycobacterium contains several slow-growing human pathogens, including Mycobacterium tuberculosis, Mycobacterium leprae, and Mycobacterium avium. Mycobacterium smegmatis is a nonpathogenic and fast growing species within this genus. In 1990, a mutant of M. smegmatis, designated mc2155, that could be transformed with episomal plasmids was isolated, elevating M. smegmatis to model status as the ideal surrogate for mycobacterial research. Classical bacterial models, such as Escherichia coli, were inadequate for mycobacteria research because they have low genetic conservation, different physiology, and lack the novel envelope structure that distinguishes the Mycobacterium genus. By contrast, M. smegmatis encodes thousands of conserved mycobacterial gene orthologs and has the same cell architecture and physiology. Dissection and characterization of conserved genes, structures, and processes in genetically tractable M. smegmatis mc2155 have since provided previously unattainable insights on these same features in its slow-growing relatives. Notably, tuberculosis (TB) drugs, including the first-line drugs isoniazid and ethambutol, are active against M. smegmatis, but not against E. coli, allowing the identification of their physiological targets. Furthermore, Bedaquiline, the first new TB drug in 40 years, was discovered through an M. smegmatis screen. M. smegmatis has become a model bacterium, not only for M. tuberculosis, but for all other Mycobacterium species and related genera. With a repertoire of bioinformatic and physical resources, including the recently established Mycobacterial Systems Resource, M. smegmatis will continue to accelerate mycobacterial research and advance the field of microbiology.

Keywords: cell envelope; distributive conjugal transfer; drug discovery; efficient plasmid transformation; leaderless mRNA; mycobacterial systems resource; mycobacteriophage; mycolic acid; phasmid; virulence factors.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

FIG 1
FIG 1
Web diagram of M. smegmatis’ role as a model organism. M. smegmatis serves applied, educational, and basic science in myriad ways. Colored ovals represent key fields that M. smegmatis contributes to, while terminal rectangular nodes represent examples of scientific contributions in each field, most of which were discussed in this review. Illustrations were created with BioRender.com.
See this image and copyright information in PMC

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